7/12 – Rob Martin’s “Daily Rain” Tuesday Evening Forecast
A near-repeat today with the downpours coming in northeast to southwest along a frontal boundary close by, with a broad, weak area of low pressure to our east aiding in the process. A secondary disturbance will drive further south on Wednesday, bringing that frontal boundary towards the area. This setup will likely produce coastal showers and storms in the morning with increasing coverage long the front late in the day through the evening hours.
As far as tropical development of that low in the Gulf, chances for that are down to 20% today (compared to 30% yesterday), which bodes well for decreasing (but not eliminating) a flood threat this week as heavy rains continue.
Flash flooding continues to be the main concern through the week, with WPC highlighting Slight Risk for portions of the area.
Thursday will just be a continuation of diurnally induced convection with storm movement likely outflow boundary driven as well as some enhancement from residual frontal boundary in place. A very stagnant pattern looks to set up across the country for the remainder of the forecast period. The upper high remains centered near AZ/NM and weakness in place over the eastern half of the country. This time of year, if there’s not strong high pressure right over the area, it’s going to be raining. That’s precisely what medium range models indicate. Thus, expecting 60-80%+ coverage each day this weekend and probably beyond that. In these setups, localized areas of flash flooding will be possible. Temperatures will remain in check, with highs typically below 90, and lows in the mid 70s.